Postmenopausal Breast Cancer Survivors Face Higher Osteoporosis Risk

By Will Boggs, MD

NEW YORK MAY 11, 2005 (Reuters Health) - Postmenopausal women who have survived early breast cancer face a higher than average risk of osteoporosis, according to a report by Canadian researchers published in the May 10th issue of the International Journal of Cancer.

"Women with breast cancer are at higher risk of osteoporosis after their treatment than the general population, especially if they are being treated with aromatase inhibitors or received chemotherapy," Dr. John R. Mackey from University of Alberta, Edmonton, told Reuters Health.

Dr. Mackey and Dr. Anil A. Joy reviewed the effects of adjuvant endocrine agents on the skeletal health of postmenopausal breast cancer patients.

Two large trials that evaluated the use of tamoxifen for breast cancer prevention showed no significant differences in the incidence of fractures in the tamoxifen and placebo groups, the authors report, though one of the trials showed an insignificant decrease in fracture risk with tamoxifen treatment.

Aromatase inhibitors, such as anastrozole, letrozole, and exemestane, are used as adjuvant therapy to suppress plasma estradiol, estrone, and estrone sulfate in patients with hormone receptor-positive tumors, the authors explain.  All have been associated with changes in bone mineral density.

Anastrozole treatment was associated with a 60% higher fracture risk than tamoxifen treatment, the report indicates. Letrozole treatment conferred a higher risk of osteoporosis than placebo treatment, and exemestane accelerated the loss of bone mineral density in the femoral neck.

Unfortunately, the investigators write, "there are no long-term clinical data available to show the effects of any of the aromatase inhibitors on fracture rates in the primary adjuvant, extended adjuvant, or the breast cancer prevention settings."

"In general, all postmenopausal women should have a baseline DXA (dual-energy X-ray absorptiometry test)," Dr. Mackey said. "However, those on tamoxifen probably don"t need aggressive repeat DXAs unless their bone mineral density is markedly low and they require more than calcium, vitamin D, and exercise."

"The timing of repeat DXA in breast cancer patients with known osteoporosis should follow established guidelines -- they should be on bisphosphonate therapy and repeat DXA every 2 years or so," Dr. Mackey concluded.

SOURCE:

• International Journal of Cancer 2005;114:1010-1015.